Film Q.

Discussion in '35mm Cameras' started by Annika1980, Mar 3, 2009.

  1. Annika1980

    Annika1980 Guest

    Remind me again .....

    I just got a few rolls of Kodak Ektar 100.
    Everything I read says to rate it at either 50 or 64 instead of 100.
    That means I set my camera's ISO to 64. OK, so far.
    Now when I have the film developed do I have the lab develop it
    normally as if it was shot at ISO 100?
    What is the difference between doing this and shooting at +2/3
    Exposure Compensation?
    Annika1980, Mar 3, 2009
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  2. If Johnny tells you to jump off a cliff ... (I'd rate it
    at 80 myself).
    Unless you're using some sort of data recording, the main
    advantage is convenience.
    Michael Benveniste, Mar 3, 2009
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  3. Doesn't the difference between ISO 50 and 64 fall well under the
    tolerance for inaccuracy in most camera's light meters? In other words,
    won't make any visible difference.

    For me, ISO 50 and 64 can be treated as identical for all practical
    purposes. Even 50 and 80 are pretty dang close (1 stop vs. ~2/3 stop

    Any system of knowledge that is capable of listing films in order
    of use of the word "****" is incapable of writing a good summary
    and analysis of the Philippine-American War. And vice-versa.
    This is an inviolable rule.

    - Matthew White, referring to Wikipedia on his WikiWatch site
    David Nebenzahl, Mar 3, 2009
  4. Annika1980

    Peter Irwin Guest

    It's true that shutters and light meters are often less accurate
    than we would like them to be, but I think the idea is to have
    a bias in favour of a generous exposure.

    Aiming towards a generous exposure of C-41 negative does three
    things for you.

    1) It improves shadow detail.
    2) It reduces apparent graininess.
    3) It makes the film's latitude more useful. C-41 film has plenty of
    overexposure latitude, but little if any underexposure latitude.

    Peter Irwin, Mar 4, 2009
  5. Yes. I routinely overexpose color negative film by 2/3 stop and seem to
    see all the benefits you listed.

    Any system of knowledge that is capable of listing films in order
    of use of the word "****" is incapable of writing a good summary
    and analysis of the Philippine-American War. And vice-versa.
    This is an inviolable rule.

    - Matthew White, referring to Wikipedia on his WikiWatch site
    David Nebenzahl, Mar 4, 2009
  6. The third point depends strictly on the manufacturers nominal
    rating as compared to physical response of the actual emulsion.
    There's no technical reason why a C-41 film exposed at the
    box rating couldn't have lots of underexposure latitude and
    only a little overexposure latitude.

    What is clear from looking at the curves of the Ektar 100
    datasheet is that overexposure will tend to emphasize blues,
    contributing to an overall cooler exposure. That's why I
    suggest that people don't rely on generalizations and rate their
    own film to their own preference.

    After my own test roll (which included bouncing my F100 off a
    sidewalk), I found that 80 was the best compromise with my Nikon
    Michael Benveniste, Mar 4, 2009
  7. Annika1980

    ^Tems^ Guest

    You gave David Nebenzahl multiple orgasms when he read that subject

    On topic TUG TUG
    On topic TUG TUG
    ^Tems^, Mar 4, 2009
  8. Annika1980

    Peter Irwin Guest

    Manufacturers rate the sensitivity of colour negative film
    according to the ISO standard. The speed of negative films
    is based on shadow sensitivity. All colour negative films
    of the same rating have the same shadow sensitivity within
    1/3 of a stop (plus or minus 1/6 of a stop from nominal rating).

    There are few cases where Kodak gives a box speed which does
    not conform to the ISO standard, but when they do this they
    are careful to print EI rather than ISO. When Kodak says the
    speed is ISO then it is.

    All modern colour negative films have considerable overexposure
    latitude. Compare the H&D graphs for a 100 speed c-41 film and
    a 100 speed e-6 film and you will invariably find that the
    c-41 film stays reasonably linear to the right of the point where
    the e-6 film goes completely clear.
    The three colours seldom (or never) track as perfectly as
    one might wish, but the overall balance in a colour print
    is always adjusted when printing. You do realise that each
    1/3 of a stop increase in exposure is a shift of 0.1 units
    to the right on the graph.
    Absolutely. You should always do your own experimentation to
    see what works best for you.

    I will have to buy some Ektar 100 soon. The claimed Print Grain
    Index figures are especially impressive. If you look at the decade
    old figures for Vericolor III 160, you will notice that the claimed
    performance from 35mm Ektar 100 is comparable to the claims for
    6x6 format vericolor III. Remarkable.

    Peter Irwin, Mar 4, 2009
  9. Annika1980

    Scott W Guest

    There should not be a difference between shooting at ISO 50 and
    shooting +1 exposure compensation.

    This might be a good time to experiment with some bracketing and see
    which exposures seem to work the best.

    My own feeling on this is that negative film tends to be very poor at
    shadow detail if you don’t expose a bit more then box calls for i.e.
    most of the latitude is on the high end with very little on the low

    I have seen some decent scans from Ektar 100 lately, it will be
    interesting to see how it compares to the 5D2

    Scott W, Mar 5, 2009
  10. Take a look at the test results at this website and see if you still
    believe that:

    The 1987 ISO standard does not define speed by shadow sensitivity per
    se. It establishes density criteria instead. The standard merely
    codified existing practice -- as far as I know not a single color
    negative films had to be reformulated or rebadged in order to meet the
    1987 standard.
    On a box of TMax-3200, what's the designation? Certainly in spec
    sheets, it's listed as an ISO-3200/36 film. They can get away with
    that because of the "recommended processing" loophole in the ISO
    Again, the site I mentioned above disagrees. They give Ektar 100 only
    2 stops of overexposure latitude, which means that if you expose it at
    an EI of 64 you'll have less overexposure latitude than underexposure.
    Superia 100 they rate at +2/-2.
    Actually, I still have some frozen Vericolor III in 70mm. Assuming I
    can find anyone who can still process the stuff, I'd like to revisit
    it someday.
    Michael Benveniste, Mar 5, 2009
  11. Annika1980

    Peter Irwin Guest

    It is going to take more than the listed results from
    to convince me that Kodak is rating their films inaccurately.
    The first ASA standard for colour negative films came out
    in 1965. The method of averaging the colour layers and the
    definition of the speed point have been rejigged since then
    but the changes were intended to be neutral for the majority
    of films. In other words, I would expect the results of the current
    method and the 1965 method to be very close in most cases.
    From memory, it doesn't say anything about ISO on the box.
    I don't have a roll right now to check.
    I just checked. The PDF spec sheets say ISO 1000 in Tmax developer,
    and ISO 800 in D-76 and most other developers. Show me which
    spec sheets say ISO 3200.
    Um, no. They can get away with saying ISO 1000 in Tmax developer,
    because the B&W standard no longer specifies a developer. It would be
    likely ASA 800 in the formerly specified developer.
    Take the negative film of your choice, either colour or black and white,
    do a series of exposures one stop apart until you get to ridiculous
    overexposures. See how many stops you have to go over before you get
    any actual highlight compression or other obvious overexposure faults.

    On the other hand, shadow detail will start to go with any level
    of underexposure. One stop over (derating by half) will almost
    always allow you to see details in the shadow areas better without
    causing any problems with the highlights. Increasing exposure will
    cause an increase in apparent contrast because you are moving
    the exposure off the toe. This may be undesirable in some cases
    especially if you are unable to reduce printing contrast slightly
    to compensate.

    I do not believe that the listed latitude ratings are meaningful.

    Peter Irwin, Mar 5, 2009
  12. Then pick up some old film shootouts from the various photo magazines,
    or go shoot some and ask your lab to measure the densities for you, or
    talk to people who rate their own film, and see if they use the same
    EI for all films with the same ISO rating.

    Kodak isn't rating films inaccurately -- the spec is simply loose
    enough to permit them to choose the nominal rating. Don't believe me?
    Compare the characteristic curve of Kodak 400NC to that for Kodak
    Vision2 250D.

    My own experience with 400UC and 400NC show them to be at 2/3rds
    of a stop apart. Similarly, I rate Fuji 160S at either 125 or 160,
    but I typically rated Portra 160 at 100.
    Within 1/6th of a stop for _all_ existing films? Not very likely.
    You're right on Kodak's spec sheets, although they've been less
    precise in consumer ads.

    In their specifications tab B&H lists both TMAX-3200 and Delta 3200 as
    ISO 3200 films. Adorama does the same.
    Specifically with Ektar 100, I found an overexposure of about 2 stops
    was sufficient to blow out the blues, resulting in the dreaded C-41
    cyan sky. And you?
    Then please feel free to provide your own data or test shots rather
    than stating generalities.
    Michael Benveniste, Mar 5, 2009
  13. Annika1980

    Peter Irwin Guest

    That's another question entirely. What is optimum to use is a different
    question from whether or not films are rated accurately. Film
    manufacturers always tell users to find their own optimum EI by testing,
    and say the ISO rating is only a starting point.
    Cine negative film speeds are covered by a different ISO standard than
    still negative films. Both will be rated to the nearest standard value
    to the measured speed.
    I bet that difference is to gain more contrast on the Portra by putting
    more of the exposure off the toe.
    From _Photographic_Sensitometry_ by Todd and Zakia (1974 ed) p.162
    "Manufacturers' published speed values necessarily include some
    tolerance. Thus an ASA Speed value of 64 represents in fact a range
    of speed values. The present standard permits a total range, at the
    time of testing, of 1/3 of a stop, so that a film rated at 64 could
    have a tested speed between 57 and 71."
    "Beyond this tolerance, any given sample of film will, by reason
    of its age and usually unknown storage conditions, have an effective
    speed perhaps considerably different from the value obtained when
    it was tested."
    Neither B&H nor Adorama make film. I haven't seen anything actually
    from Kodak which claims 3200 as the ISO speed.
    I haven't used Ektar 100 yet. I don't doubt that you saw what you
    describe. I do doubt that it had anything to do with overexposure.
    I think it highly probable that this is a side effect of moving
    the shadow values up off the toe thus increasing the overall
    contrast with the result that the same printing contrast didn't
    give enough room on the paper for the highlights.
    My three generalities were useful, and were things I did not
    know when staring out.

    With colour negative film
    - a small increase in exposure gives better detail in the shadows
    - a small increase in exposure results in a decrease in apparent grain
    - a small increase in exposure reduces the risk of underexposure
    and that the risk of underexposing negative films is greater than
    the risk of overexposure thus giving more useful latitude.

    I should also have noted that increasing exposure increases the
    contrast in the shadows which can sometimes have undesirable
    consequences and that increased exposure also makes film very
    slightly less sharp, although this is scarcely noticeable unless
    you go seriously overboard.

    Peter Irwin, Mar 5, 2009
  14. Annika1980

    Colin.D Guest

    Calibration may be out a bit with any given meter, but the repeatability
    should be pretty accurate. You should always test a film against your
    meter to find the best setting for your camera, after which the meter
    should be as accurate as you want.

    Professional meters like the Sekonic range for example are guaranteed
    accurate to within 1/10 of a stop, provided it is used intelligently.

    Colin D.
    Colin.D, Mar 5, 2009
  15. This whole exchange you two are having is very enlightening (what parts
    of it aren't whizzing over my head). Please don't stop.

    Made From Pears: Pretty good chance that the product is at least
    mostly pears.
    Made With Pears: Pretty good chance that pears will be detectable in
    the product.
    Contains Pears: One pear seed per multiple tons of product.

    (with apologies to Dorothy L. Sayers)
    David Nebenzahl, Mar 5, 2009
  16. If ISO is as accurate as you claim, such tests would result
    in the same EI for all films of a given ISO. They don't.
    And that standard is? For the 250D movie film, Kodak states:
    "Use these indexes with incident- or reflected-light exposure
    meters and cameras marked for ISO or ASA speeds or exposure
    So from this statement, we see that ISO for movie photography
    should equate to ASA, which covered both markets. You claim
    that ASA and ISO for still camera film are also equivalent. If
    A=B and B=C, then why doesn't A=C?

    One uses the same exposure meters and settings for movie or
    still photography. I haven't shot 250D in a film camera, but I
    have shot Fuji Eterna 500T. The "grain" was about the same as
    Fuji NPZ, but I found it was true to its 500 speed badging.
    When I'm using a film like 160S, I'm not interested in gaining
    You're confusing precision and accuracy. ASA defined one method
    of measurement, specifying a precision of 1/3rd of a stop. Yet
    under those methods, original Tri-X was marketed at either two or
    three different speeds. ISO also specifies a precision of 1/3rd
    of a stop, but requires different measurements. Both specs had
    and have plenty of slop.
    Here's one such flyer:
    So inaccurate recording of color doesn't qualify as overexposure
    by your definition? Then we should agree to disagree.
    The site I referred to provided data from actual tests, which
    you claim are not meaningful. So please provide meaningful
    data to support your generalities.
    Michael Benveniste, Mar 5, 2009
  17. Annika1980

    Doug Jewell Guest

    Just grabbed a box out of the fridge - here is what it says:
    Kodak Professional
    T-MAX P3200 FILM
    Black & White Negative Film
    Film Negatif Noir Et Blanc
    Schwarzweiss Negativ Film
    Pelicula Negativa En Blanco Y Negro

    Kodak Professional
    T-MAX P3200 FILM
    P3200 TMAX
    Black & White Negative Film
    Film Negatif Noir Et Blanc
    135-36 P3200TMZ

    The other end is the same except in foreign language.

    Kodak Olympic Sponsor Symbol.
    T-Max P3200 Film

    36 EXP
    CAT 151 6798
    Made In USA
    Finished in Mexico for
    Rochester NY 14650

    Limitation of Liability: blah blah blah
    Expiry Date...

    EXPIRY 05/2007... FLAMIN HELL!!!
    I bought a pack just before my youngest kid was born to do
    some nice grainy baby photos. He's now 2-1/2, and the pack
    is untouched. Time to get some batteries for the film camera
    and start snapping I think. I hope my developer and fixer
    are still good.

    In answer to the original discussion, there is nothing on
    the box that actuall says "ISO 3200", although it is
    certainly inferred by the repeated use of "P3200". The DX
    coding on the film is 3200, if that means anything. I've
    always shot it at 3200, because I like the look that it
    gives at that speed. I don't know and don't care what the
    true ISO rating of the film is - 3200 gives results that I
    like. If I didn't want the look that P3200 gives at 3200,
    I'd shoot something else.
    Doug Jewell, Mar 5, 2009
  18. Annika1980

    Peter Irwin Guest

    There seem to be several issues packed together here.
    - Are ISO ratings the nearest standard value to what the film
    actually was tested at? (Yes)
    - Are the ISO ratings of negative films a valid indicator of
    the useful response of the film in the toe, so that two films
    of the same rating will have about equal shadow detail for
    the same exposure? (I think yes)
    - Do the two points above mean that you can determine the exposure
    which will get the results you want entirely from the ISO speed
    rating? (No)
    I was wrong about this. There is no ISO speed for cine negative films.
    There seems not to be a standard on purpose. (The standard for reversal
    films covers both still and cine films, but the standards for negative
    films specify still films only.) Kodak's cine negative films all carry
    an EI rating in their datasheets. I haven't been able to find out what
    Kodak's rules are for rating cine negatives, but they seem generally
    to be 2/3 of a stop under what the ISO speed rating would be if they
    were still films. Thus Plus-X cine negative is rated at EI 80, but is
    the same speed (though not exactly the same film) as Plus-x 125 for
    35mm still cameras. The EI 250 cine films seem to be about the speed
    of ISO 400 still negative films.
    The meters are the same. Exposing cine negatives at the rating
    system used for still negative camera films would give you
    degraded blacks. You have probably noticed that reversal films
    of a given speed rating tend to be much better at picking up
    shadow detail. Kodachrome 64 will give you a bit better shadow detail
    at box speed than ISO 100 colour negative film shot at EI64.
    If you are going to make a transparency for projection from
    negative film shot at the ISO speed rating, you will probably
    find the film underexposed for that purpose. ISO speed for negative
    films is supposed to be the minimum exposure required to produce
    a reflection print rated as excellent. The same exposure is probably
    inadequate for making a transparency for projection.
    Interesting, how did you do the subjective comparison?
    If my belief is correct about cine films being rated
    conservatively then Eterna 500T should be more than
    1 stop faster than NPZ+80A conversion filter. If it is
    only equal to ISO 500 then it should be less than one
    stop faster than ISO 800 speed negative plus an 80A filter.

    Note that if you are shooting tungsten balanced negative film
    or daylight film plus an 80A then you need a little extra
    exposure with 2800K household incandescents to get enough blue
    on the film. It does seem that Kodak got it wrong on a Chinese language webpage.
    Thanks for pointing that out. It would seem to indicate that it is
    something that Kodak promotional material very rarely gets wrong.

    Peter Irwin, Mar 9, 2009
  19. I'm not sure what you're saying here. The ISO rating is a
    summary statistic of a test, but that doesn't speak to the
    accuracy of that test.
    The ISO standard says nothing about the shape of the curve, and
    the ASA measurement specifically ignored the toe when rating
    a film.

    But to test your claim, compare the curves for Fuji Reala 100
    and Fuji Superia 100. The manufacturer, exposure and methods
    and resulting ISO ratings are the same; the toes are markedly
    Ah, Plus-X. Initially marketed as an ASA 80 film, it then changed
    to an ASA 160 film, and finally settled in at 125. But Kodak 5231/
    7231 and PXP are the same stuff -- only the aerial stuff is different.
    If you're willing to load it yourself in a changing bag or darkroom,
    you can often buy "short ends" of Kodak 5231 for under $0.20 a foot.
    Then shoot and process normally.

    Once again we find that in other markets, Kodak does refer to 5231/7231
    as an ISO 80 film:

    But here the difference in recommended shooting speeds is easily
    explained. Kodak recommends EI 80 for D-96 developer. D-96 has less
    metol and hydroquinone than D-76, so it isn't surprising that the
    output is different. There's no such discrepency between ECN-II and
    C-41 chemistry.

    The Aerecon version has extended red sensitivity and gets yet a
    different rating (200) on yet a different ISO scale (ISO-A) for
    a different developer. I've never tried it, and with a minimum order
    of 500' in 70mm I'm not likely to. But I have tried Agfa Aviphot
    N400, which is a C-41 film. That film was rated at 400 via both the
    ISO-A and ISO methods, and did well in my Pentax 645 at rated speed.
    I certainly wouldn't rate it any lower.
    By "degraded blacks," do you mean loss of shadow detail?
    Underexposing would make the blacks even blacker.

    In the past, several labs offered a service to create slides
    as well as negatives from C-41 film. Dale labs still does.
    While such slides suffer from the usual "2nd generation" issues,
    loss of shadow detail was not a significant problem.

    Nor does the difference in workflow explain the difference
    in recommendations. When movies shifted from using optical
    intermediate films to a digital intermediate process, the
    EI of camera films didn't change at all.
    I compared grain by scanning both films with a Canon FS4000US.
    I determined exposure by bracketing and verifying incident
    light with a Minolta V light meter.

    The grain comparison was against NPZ shot in daylight -- I
    gave up on trying to use 80A filters long ago.

    I've shot the 500T under 3200K photofloods, stage lighting,
    and room lighting. It's a bit warm under room lighting, as
    expected. I've still got about 100' left of the stuff in
    the freezer, so I can spool up some more if you want to give
    it a try.
    Michael Benveniste, Mar 9, 2009
  20. Annika1980

    Annika1980 Guest

    And therein lies the main difference between film and digital!
    The digital shooters want high Megapixels, low noise, and anything
    else that will give them the best shot.
    The film shooters worry about the shape of the toes on the film
    Annika1980, Mar 10, 2009
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